In recent years, technologies for wireless sensor networks have actively been developed. Wireless sensor networks are technologies for collecting people's behavior information or surrounding environment information, for example, by connecting wireless nodes in which wireless devices and sensor devices such as position sensors or temperature sensors are combined, to wireless networks. Wireless sensor networks are expected to be utilized in various fields such as monitoring systems and home automation. This is because advantages such as flexibility of reduction in cost, expansion of sensing ranges, and changes in networks can be expected when sensor networks are constructed with wireless communication.
Wireless sensor network systems can be considered to be designed variously depending on which is preferred among requests of applications to be applied. Examples of the requests include the amount of information of data and a direction of the data to be exchanged, a scale of the capacity of wireless nodes per base station, an extent of a communicable area, complexity of signal processing on a wireless node side, a transmission delay time, tolerance for mobility of a wireless node, reliability of data transmission, and addition of a base station or a wireless node.
The following Non-Patent Literature 1 is a technical specification regarding a wireless local area network (LAN) drawn up by the IEEE. The following Non-Patent Literature 1 discloses a technology for resolving a so-called hidden terminal problem in which waves transmitted from wireless nodes having a positional relation in which mutual transmitted radio waves may not be detected collide in order to improve reliability of data transmission. Examples of such a technology include a technology for providing a controlled access by which a base station schedules transmission and reception of subordinate wireless nodes and a technology for transmitting request to send/clear to send (RTS/CTS).